not really sure what to tell you, but I do know Aquamark is not intended for the general public. Have you tried the actual Aquanox game?
Also, what video card do you have. I used to run Aquanox with Radeon8500, and it would crash very regularly. I switched to GF4 TI4400 and all my problems went away. I run Aquanox at 1024x768 with max details on everything (even plankton) and I've no complaints, smooth as a baby's... well you get the idea